1. Field of the Invention
The invention relates generally to code readers and particularly to readers which sense optically discernible symbol combinations or codes, such as bar codes and two-dimensional codes.
2. Discussion of the Related Art
Hand-held optical character reading equipment that has been available in the past has not performed well. The reader must be positioned and/or displaced accurately relative to the label for a valid read to occur. Operators usually "scrub" the label with the reader rather than carefully aligning the reader on the label, and often give up and manually key the information into the terminal.
The primary reason that accurate alignment is required is that the reader uses either a linear matrix of sensing elements, say sixty-four, or a rectangular matrix of sensing elements, say fourteen by forty. The recognition algorithms typically used in some of these systems assume that the sensor is oriented accurately over or across the character to be read with a misalignment of less than a relatively small angle. It is not surprising that few operators use the readers in this way, and that poor read rates and dissatisfaction with the criticality of the reader alignment during scanning, have been serious problems.
Although some progress has been made in the development of an optical character reader (OCR) product that has the capability to be operated portably, power consumption and circuit complexity remain as factors that have hindered development in this area.
Another complication with existing readers is the use of scanners by unskilled operators, or by operators who attempt to scan in haste due to an overburdened work schedule. As a result, inaccurate readings are taken which must be repeated, thereby losing some of the efficiency which might otherwise be available and which unnecessarily places a strain on available electrical enery.
What is needed is a reliable hand-held optical reader that prevents activation of the reader until it is within an acceptable range from a target area.